Laser capsulovitreotomy

ABSTRACT

Methods and systems for performing laser-assisted surgery on an eye form a layer of bubbles in the Berger&#39;s space of the eye to increase separation between the posterior portion of the lens capsule of the eye and the anterior hyaloid surface of the eye. A laser is used to form the layer of bubbles in the Berger&#39;s space. The increased separation between the posterior portion of the lens capsule and the anterior hyaloid surface can be used to facilitate subsequent incision of the posterior portion of the lens capsule with decreased risk of compromising the anterior hyaloid surface. For example, the layer of bubbles can be formed prior to performing a capsulotomy on the posterior portion of the lens capsule.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 14/190,915, filed Feb. 26, 2014, which claimspriority to U.S. provisional application No. 61/785,672 filed on Mar.14, 2013, the entire contents of which are incorporated herein byreference.

BACKGROUND

Cataract extraction is one of the most commonly performed surgicalprocedures in the world. A cataract is formed by opacification of thecrystalline lens or its envelope—the lens capsule—of the eye. Thecataract obstructs passage of light through the lens. A cataract canvary in degree from slight to complete opacity. Early in the developmentof an age-related cataract the power of the lens may be increased,causing near-sightedness (myopia). Gradual yellowing and opacificationof the lens may reduce the perception of blue colors as thosewavelengths are absorbed and scattered within the crystalline lens.Cataract formation typically progresses slowly resulting in progressivevision loss. Cataracts are potentially blinding if untreated.

A common cataract treatment involves replacing the opaque crystallinelens with an artificial intraocular lens (IOL). Presently, an estimated15 million cataract surgeries per year are performed worldwide. Thecataract treatment market is composed of various segments includingintraocular lenses for implantation, viscoelastic polymers to facilitatesurgical maneuvers, and disposable instrumentation including ultrasonicphacoemulsification tips, tubing, various knives, and forceps.

Presently, cataract surgery is typically performed using a techniquetermed phacoemulsification in which an ultrasonic tip with associatedirrigation and aspiration ports is used to sculpt the relatively hardnucleus of the lens to facilitate removal through an opening made in theanterior lens capsule. The nucleus of the lens is contained within anouter membrane of the lens that is referred to as the lens capsule.Access to the lens nucleus can be provided by performing an anteriorcapsulotomy in which a small round hole is formed in the anterior sideof the lens capsule. Access to the lens nucleus can also be provided byperforming a manual continuous curvilinear capsulorhexis (CCC)procedure. After removal of the lens nucleus, a synthetic foldableintraocular lens (IOL) can be inserted into the remaining lens capsuleof the eye through a small incision. Typically, the IOL is held in placeby the edges of the anterior capsule and the capsular bag. The IOL mayalso be held by the posterior capsule, either alone or in unison withthe anterior capsule. This latter configuration is known in the field asa “Bag-in-Lens” implant.

One of the most technically challenging and critical steps in thecataract extraction procedure is providing access to the lens nucleus.The manual continuous curvilinear capsulorhexis (CCC) procedure evolvedfrom an earlier technique termed can-opener capsulotomy in which a sharpneedle was used to perforate the anterior lens capsule in a circularfashion followed by the removal of a circular fragment of lens capsuletypically in the range of 5-8 mm in diameter. The smaller thecapsulotomy, the more difficult it is to produce manually. Thecapsulotomy facilitates the next step of nuclear sculpting byphacoemulsification. Due to a variety of complications associated withthe initial can-opener technique, attempts were made by leading expertsin the field to develop a better technique for removal of the anteriorlens capsule preceding the emulsification step.

The desired outcome of the manual continuous curvilinear capsulorhexisis to provide a smooth continuous circular opening through which notonly the phacoemulsification of the nucleus can be performed safely andeasily, but also to provide for easy insertion of the intraocular lens.The resulting opening in the anterior capsule provides both a clearcentral access for tool insertion during removal of the nucleus and forIOL insertion, a permanent aperture for transmission of the image to theretina of the patient, and also support of the IOL inside the remainingcapsule that limits the potential for dislocation.

Furthermore, IOLs that engage the posterior capsule can benefit from aposterior capsulotomy. An example of such an IOL that can benefit from aposterior capsulotomy is described in U.S. Pat. Appl. No. 2008/0281413,entitled “METHOD AND APPARATUS FOR CREATING INCISIONS TO IMPOROVEINTRAOCULAR LENS PLACEMENT”, in the name of Culbertson, et al., theentire disclosure of which is incorporated herein by reference. Suchlenses may further benefit from seating the IOL in both the anterior andposterior capsule in order to best provide for accommodative motion viathe zonular process. Creating a posterior capsulotomy, however, mayrequire the surgeon to engage the vitreous and its anterior hyaloidsurface. Unfortunately, the anterior hyaloid surface may be violatedduring the posterior capsulotomy procedure. It is postulated that abroken anterior hyaloid surface may allow anterior movement of proteinsand macromolecules from the vitreous gel, which may result in fluidshifting within an already syneretic vitreous cavity. This anteriormovement of proteins and macromolecules may lead to increased peripheralretinal traction and break formation. Even with an intact anteriorhyaloid surface, a rent in the posterior capsule disrupts the physicalbarrier between the anterior and posterior segments of the eye similarto that of the aphakic eye after intracapsular lens extraction. The lossof this barrier may facilitate diffusion of hyaluronic acid, astabilizer of the vitreous gel, into the anterior chamber; thissituation may manifest clinically as collapse of the vitreous gel.

Accordingly, improved methods, techniques, and an apparatus are neededto perform an accurate posterior capsulotomy with reduced risk ofcompromising the anterior hyaloid surface.

SUMMARY

Although specific reference is made to the removal and treatment of acataract, the methods and apparatus as described herein can be used withone or more of many surgical procedures, for example a posteriorcapsulotomy on a non-cataractous eye of a patient.

Embodiments provide methods and systems for performing laser-assistedsurgery on an eye to provide a separation layer between the posteriorportion of the lens capsule of the eye and the anterior hyaloid surfaceof the eye. While the separation layer can be formed in one or more ofmany ways, in many embodiments a layer of bubbles is formed in theBerger's space of the eye to separate the posterior portion of the lenscapsule of the eye and the anterior hyaloid surface of the eye. Theincreased separation between the posterior portion of the lens capsuleand the anterior hyaloid surface reduces the risk of compromising theanterior hyaloid surface during a subsequent procedure in which theposterior portion of the lens capsule is incised. In many embodiments,the layer of bubbles is formed prior to performing a capsulotomy on theposterior portion of the lens capsule. The capsulotomy can be performedin combination with one or more of many surgical procedures, such as theimplantation of an IOL which may comprise an accommodating IOL or anon-accommodating IOL.

Thus, in one aspect, a method is provided for performing laser-assistedsurgery on an eye having a lens capsule, an anterior hyaloid surface,and a Berger's space between a posterior portion of the lens capsule andthe anterior hyaloid surface. The method includes using a laser to formbubbles within the Berger's space to increase separation between theposterior portion of the lens capsule and the anterior hyaloid surface.After forming the bubbles, the posterior portion of the lens capsule inincised. In many embodiments, the laser is used to perform the incisingof the posterior portion of the lens capsule. And in many embodiments,the laser is used to perform a capsulotomy on the posterior portion ofthe lens capsule.

In another aspect, a system is provided for performing laser-assistedsurgery on an eye having a lens capsule, an anterior hyaloid surface,and a Berger's space between a posterior portion of the lens capsule andthe anterior hyaloid surface. The system includes a laser source, anintegrated optical system, and a controller. The laser source isconfigured to produce a treatment beam including a plurality of laserpulses. The integrated optical system includes an imaging assemblyoperatively coupled to a treatment laser delivery assembly such thatthey share at least one common optical element. The integrated opticalsystem is configured to acquire image information pertinent to one ormore targeted tissue structures and direct the treatment beam in athree-dimensional pattern to cause breakdown in at least one of thetargeted tissue structures. The controller is operatively coupled withthe laser source and the integrated optical system. The controller isconfigured to control the system to form a plurality of bubbles withinthe Berger's space to increase separation between the posterior portionof the lens capsule and the anterior hyaloid surface. In manyembodiments, the controller is configured to control the system toincise the posterior portion of the lens capsule subsequent to theformation of the plurality of bubbles within the Berger's space. And inmany embodiments, the controller is configured to control the system toperform a capsulotomy on the posterior portion of the lens capsulesubsequent to the formation of the plurality of bubbles within theBerger's space.

For a fuller understanding of the nature and advantages of the presentdisclosure, reference should be made to the ensuing detailed descriptionand accompanying drawings. Other aspects, objects and advantages of thedisclosure will be apparent from the drawings and detailed descriptionthat follows.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the features and advantages of the presentdisclosure will be obtained by reference to the following detaileddescription that sets forth illustrative embodiments, in which theprinciples of the disclosure are utilized, and the accompanying drawingsof which:

FIG. 1 shows a schematic representation of an embodiment of a systemcapable of creating bubbles within the anterior hyaloid vitreous ofBerger's space, in accordance with many embodiments;

FIG. 2 shows a schematic representation of another embodiment of asystem, which utilizing optical multiplexing to deliver treatment andimaging light, that is capable of creating bubbles within the anteriorhyaloid vitreous of Berger's space, in accordance with many embodiments;

FIG. 3 shows a schematic representation of another embodiment of asystem capable of creating bubbles within the anterior hyaloid vitreousof Berger's space utilizing an alternate imaging system configuration,in accordance with many embodiments;

FIG. 4 shows a schematic representation of another embodiment of asystem capable of creating bubbles within the anterior hyaloid vitreousof Berger's space utilizing another alternate imaging systemconfiguration, in accordance with many embodiments;

FIG. 5 is a schematic representation of the anterior chamber, lens, andanterior vitreous of the eye, in accordance with many embodiments;

FIG. 6 shows a schematic representation the use of a laser to create abubble within the anterior hyaloid vitreous of Berger's space, inaccordance with many embodiments;

FIG. 7 shows a schematic representation of a layer of bubbles createdwithin the anterior hyaloid vitreous of Berger's space, in accordancewith many embodiments; and

FIG. 8 illustrates a method for using a laser to form a layer of bubbleswithin the Berger's space of an eye to increase separation between theposterior portion of the lens capsule and the anterior hyaloids surfaceand, after forming the layer of bubbles, incising the posterior portionof the lens capsule, in accordance with many embodiments.

DETAILED DESCRIPTION

In the following description, various embodiments of the presentdisclosure will be described. For purposes of explanation, specificconfigurations and details are set forth in order to provide a thoroughunderstanding of the embodiments. However, it will also be apparent toone skilled in the art that the present disclosure may be practicedwithout the specific details. Furthermore, well-known features may beomitted or simplified in order not to obscure the embodiment beingdescribed.

Methods and systems for performing laser-assisted surgery on an eye usea laser form a layer of bubbles in the Berger's space of the eye. Thelayer of bubbles serves to increase separation between the posteriorportion of the lens capsule of the eye and the anterior hyaloid surfaceof the eye. The increased separation between the posterior portion ofthe lens capsule and the anterior hyaloid surface can be used todecrease risk of compromising the anterior hyaloid surface during asubsequent incision of the posterior portion of the lens capsule. Forexample, the layer of bubbles can be formed prior to performing acapsulotomy on the posterior portion of the lens capsule.

The methods disclosed herein can be implemented by a system thatprojects or scans an optical beam into a patient's eye 68, such assystem 2 shown in FIG. 1. System 2 includes an ultrafast (UF) lightsource 4 (e.g., a femtosecond laser). Using system 2, a beam can bescanned in the patient's eye 68 in three dimensions: X, Y, Z.Short-pulsed laser light can be focused into eye tissue to producedielectric breakdown to cause photo disruption around the focal point(the focal zone), thereby rupturing the tissue in the vicinity of thephoto-induced plasma. In this embodiment, the wavelength of the laserlight can vary between 800 nm to 1200 nm and the pulse width of thelaser light can vary from 10 fs to 10000 fs. The pulse repetitionfrequency can also vary from 10 kHz to 500 kHz. Safety limits withregard to unintended damage to non-targeted tissue bound the upper limitwith regard to repetition rate and pulse energy. And threshold energy,time to complete the procedure, and stability bound the lower limit forpulse energy and repetition rate. The peak power of the focused spot inthe eye 68 and specifically within the crystalline lens 69 and anteriorcapsule of the eye is sufficient to produce optical breakdown andinitiate a plasma-mediated ablation process. Near-infrared wavelengthsare preferred because linear optical absorption and scattering inbiological tissue is reduced for near-infrared wavelengths. As anon-limiting example, laser 4 can be a repetitively pulsed 1035 nmdevice that produces 500 fs pulses at a repetition rate of 100 kHz andindividual pulse energy in the 1 to 20 micro joule range.

Alternately, a system of longer pulse duration and higher energy can beused to create larger bubbles for enhanced efficiency. Using a supinepatient, the resulting bubbles will float upwards. This reduces theaccuracy requirement of the targeting system. In general, any suitablelaser having any suitable parameters can be used.

The laser 4 is controlled by control electronics 300, via an input andoutput device 302, to create optical beam 6. Control electronics 300 maycomprise a processor such as a computer, microcontroller, etc. In thisexample, the controller 300 controls the entire system and data is movedthrough input/output device IO 302. A graphical user interface GUI 304can be used to set system operating parameters, process user input (UI)306, and display gathered information such as images of ocularstructures. The GUI 304 and UI 306 may comprise components of a knowncomputer system, for example one or more of a display, a touch screendisplay, key board, a pointer or a mouse, for example. The controlelectronics may comprise one or more processors of a computer system,for example.

The control electronics 300 can be configured in one or more of manyways, and may comprise a processor having a tangible medium havinginstructions of a computer program embodied thereon. In manyembodiments, the tangible medium comprises a computer readable memoryhaving instructions of a computer readable medium embodied thereon.Alternatively or in combination, the control electronic may comprisearray logic such as a gate array, a programmable gate array, for fieldprogrammable gate array to implement one or more instructions asdescribed herein. The instructions of the tangible medium can beimplemented by the processor of the control electronics.

The generated UF light beam 6 proceeds towards the patient eye 68passing through a half-wave plate 8 and a linear polarizer, 10. Thepolarization state of the beam can be adjusted so that the desiredamount of light passes through the half-wave plate 8 and the linearpolarizer 10, which together act as a variable attenuator for the UFbeam 6. Additionally, the orientation of the linear polarizer 10determines the incident polarization state incident upon a beam combiner34, thereby optimizing the beam combiner 34 throughput.

The UF light beam 6 proceeds through a system-controlled shutter 12, anaperture 14, and a pickoff device 16. The system-controlled shutter 12ensures on/off control of the laser for procedural and safety reasons.The aperture 14 sets an outer useful diameter for the UF light beam 6and the pickoff device 16 monitors the resulting beam. The pickoffdevice 16 includes a partially reflecting mirror 20 and a detector 18.Pulse energy, average power, or a combination can be measured using thedetector 18. Output from the detector 18 can be used for feedback to thehalf-wave plate 8 for attenuation and to verify whether thesystem-controlled shutter 12 is open or closed. In addition, thesystem-controlled shutter 12 can have position sensors to provide aredundant state detection.

The beam passes through a beam conditioning stage 22, in which beamparameters such as beam diameter, divergence, circularity, andastigmatism can be modified. In this illustrative example, the beamconditioning stage 22 includes a two-element beam expanding telescopecomprised of spherical optics 24, 26 in order to achieve the intendedbeam size and collimation. Although not illustrated here, an anamorphicor other optical system can be used to achieve the desired beamparameters. The factors used to determine these beam parameters includethe output beam parameters of the laser, the overall magnification ofthe system, and the desired numerical aperture (NA) at the treatmentlocation. In addition, the beam conditioning stage 22 can be used toimage aperture 14 to a desired location (e.g., the center locationbetween a 2-axis scanning device 50 described below). In this way, theamount of light that makes it through the aperture 14 is assured to makeit through the scanning system. The pickoff device 16 is then a reliablemeasure of the usable light.

After exiting the beam conditioning stage 22, the beam 6 reflects off offold mirrors 28, 30, 32. These mirrors can be adjustable for alignmentpurposes. The beam 6 is then incident upon the beam combiner 34. Thebeam combiner 34 reflects the UF beam 6 (and transmits both the imaging,in this exemplary case, an optical coherence tomography (OCT) beam 114,and an aim 202 beam described below). For efficient beam combineroperation, the angle of incidence is preferably kept below 45 degreesand the polarization of the beams is fixed where possible. For the UFbeam 6, the orientation of the linear polarizer 10 provides fixedpolarization. Although OCT is used as the imaging modality in thisnon-limiting example, other approaches, such as Purkinje imaging,Scheimpflug imaging, confocal or nonlinear optical microscopy,fluorescence imaging, ultrasound, structured light, stereo imaging, orother known ophthalmic or medical imaging modalities and/or combinationsthereof may be employed.

Following the beam combiner 34, the beam 6 continues onto a z-adjust orZ scan device 40. In this illustrative example the z-adjust 40 includesa Galilean telescope with two lens groups 42, 44 (each lens groupincludes one or more lenses). The lens group 42 moves along the z-axisabout the collimation position of the telescope. In this way, the focusposition of the spot in the patient's eye 68 moves along the z-axis asindicated. In general, there is a fixed linear relationship between themotion of lens 42 and the motion of the focus. In this case, thez-adjust telescope has an approximate 2× beam expansion ratio and a 1:1relationship of the movement of lens 42 to the movement of the focus.Alternatively, the lens group 44 could be moved along the z-axis toactuate the z-adjust, and scan. The z-adjust 40 is the z-scan device fortreatment in the eye 68. It can be controlled automatically anddynamically by the system and selected to be independent or to interplaywith the X-Y scan device described next. The mirrors 36, 38 can be usedfor aligning the optical axis with the axis of the z-adjust device 40.

After passing through the z-adjust device 40, the beam 6 is directed tothe x-y scan device 50 by mirrors 46, 48. The mirrors 46, 48 can beadjustable for alignment purposes. X-Y scanning is achieved by thescanning device 50 preferably using two mirrors 52, 54 under the controlof the control electronics 300, which rotate in orthogonal directionsusing motors, galvanometers, or any other well known optic movingdevice. The mirrors 52, 54 are located near the telecentric position ofan objective lens 58 and a contact lens 66 combination described below.Tilting the mirrors 52, 54 changes the resulting direction of the beam6, causing lateral displacements in the plane of UF focus located in thepatient's eye 68. The objective lens 58 may be a complex multi-elementlens element, as shown, and represented by lenses 60, 62, and 64. Thecomplexity of the objective lens 58 will be dictated by the scan fieldsize, the focused spot size, the available working distance on both theproximal and distal sides of objective lens 58, as well as the amount ofaberration control. An f-theta objective lens 58 of focal length 60 mmgenerating a spot size of 10 μm, over a field of 10 mm, with an inputbeam size of 15 mm diameter is an example. Alternatively, X-Y scanningby the scanning device 50 may be achieved by using one or more moveableoptical elements (e.g., lenses, gratings), which also may be controlledby the control electronics 300, via the input and output device 302.

The scanning device 50 under the control of the control electronics 300can automatically generate the aiming and treatment scan patterns. Suchpatterns may be comprised of a single spot of light, multiple spots oflight, a continuous pattern of light, multiple continuous patterns oflight, and/or any combination of these. In addition, the aiming pattern(using the aim beam 202 described below) need not be identical to thetreatment pattern (using the light beam 6), but preferably at leastdefines its boundaries in order to assure that the treatment light isdelivered only within the desired target area for patient safety. Thismay be done, for example, by having the aiming pattern provide anoutline of the intended treatment pattern. This way the spatial extentof the treatment pattern may be made known to the user, if not the exactlocations of the individual spots themselves, and the scanning thusoptimized for speed, efficiency and accuracy. The aiming pattern mayalso be made to be perceived as blinking in order to further enhance itsvisibility to the user.

An optional contact lens 66, which can be any suitable ophthalmic lens,can be used to help further focus the light beam 6 into the patient'seye 68 while helping to stabilize eye position. The positioning andcharacter of the light beam 6 and/or the scan pattern the light beam 6forms on the eye 68 may be further controlled by use of an input devicesuch as a joystick, or any other appropriate user input device (e.g.,GUI 304) to position the patient and/or the optical system.

The UF laser 4 and the control electronics 300 can be set to target thetargeted structures in the eye 68 and ensure that the light beam 6 willbe focused where appropriate and not unintentionally damage non-targetedtissue. Imaging modalities and techniques described herein, such asthose mentioned above, or ultrasound may be used to determine thelocation and measure the thickness of the lens and lens capsule toprovide greater precision to the laser focusing methods, including 2Dand 3D patterning. Laser focusing may also be accomplished using one ormore methods including direct observation of an aiming beam, or otherknown ophthalmic or medical imaging modalities, such as those mentionedabove, and/or combinations thereof. In the embodiment of FIG. 1, an OCTdevice 100 is described, although other modalities are within the scopeof the present disclosure. An OCT scan of the eye will provideinformation about the axial location of the anterior and posterior lenscapsule, the boundaries of the cataract nucleus, as well as the depth ofthe anterior chamber. This information is then loaded into the controlelectronics 300, and used to program and control the subsequentlaser-assisted surgical procedure. The information may also be used todetermine a wide variety of parameters related to the procedure such as,for example, the upper and lower axial limits of the focal planes usedfor cutting the lens capsule and segmentation of the lens cortex andnucleus, and the thickness of the lens capsule among others.

The OCT device 100 in FIG. 1 includes a broadband or a swept lightsource 102 that is split by a fiber coupler 104 into a reference arm 106and a sample arm 110. The reference arm 106 includes a module 108containing a reference reflection along with suitable dispersion andpath length compensation. The sample arm 110 of the OCT device 100 hasan output connector 112 that serves as an interface to the rest of theUF laser system. The return signals from both the reference and samplearms 106, 110 are then directed by coupler 104 to a detection device128, which employs a time domain detection technique, a frequencydetection technique, or a single point detection technique. In FIG. 1, afrequency domain technique is used with an OCT wavelength of 830 nm andbandwidth of 100 nm.

After exiting the connector 112, the OCT beam 114 is collimated using alens 116. The size of the collimated OCT beam 114 is determined by thefocal length of the lens 116. The size of the beam 114 is dictated bythe desired NA at the focus in the eye and the magnification of the beamtrain leading to the eye 68. Generally, the OCT beam 114 does notrequire as high an NA as the UF light beam 6 in the focal plane andtherefore the OCT beam 114 is smaller in diameter than the UF light beam6 at the beam combiner 34 location. Following the collimating lens 116is an aperture 118, which further modifies the resultant NA of the OCTbeam 114 at the eye. The diameter of the aperture 118 is chosen tooptimize OCT light incident on the target tissue and the strength of thereturn signal. A polarization control element 120, which may be activeor dynamic, is used to compensate for polarization state changes. Thepolarization state changes may be induced, for example, by individualdifferences in corneal birefringence. Mirrors 122, 124 are then used todirect the OCT beam 114 towards beam combiners 126, 34. Mirrors 122, 124can be adjustable for alignment purposes and in particular foroverlaying of the OCT beam 114 to the UF light beam 6 subsequent to thebeam combiner 34. Similarly, the beam combiner 126 is used to combinethe OCT beam 114 with the aim beam 202 as described below.

Once combined with the UF light beam 6 subsequent to beam combiner 34,the OCT beam 114 follows the same path as the UF light beam 6 throughthe rest of the system. In this way, the OCT beam 114 is indicative ofthe location of the UF light beam 6. The OCT beam 114 passes through thez-scan 40 and x-y scan 50 devices then the objective lens 58, thecontact lens 66, and on into the eye 68. Reflections and scatter off ofstructures within the eye provide return beams that retrace back throughthe optical system, into the connector 112, through the coupler 104, andto the OCT detector 128. These return back reflections provide OCTsignals that are in turn interpreted by the system as to the location inX, Y, and Z of UF light beam 6 focal location.

The OCT device 100 works on the principle of measuring differences inoptical path length between its reference and sample arms. Therefore,passing the OCT beam 114 through the z-adjust device 40 does not extendthe z-range of the OCT system 100 because the optical path length doesnot change as a function of movement of the lens group 42. The OCTsystem 100 has an inherent z-range that is related to the detectionscheme, and in the case of frequency domain detection it is specificallyrelated to the spectrometer and the location of the reference arm 106.In the case of OCT system 100 used in FIG. 1, the z-range isapproximately 1-2 mm in an aqueous environment. Extending this range toat least 4 mm involves the adjustment of the path length of thereference arm within OCT system 100. Passing the OCT beam 114 in thesample arm through the z-scan of z-adjust device 40 allows foroptimization of the OCT signal strength. This is accomplished byfocusing the OCT beam 114 onto the targeted structure whileaccommodating the extended optical path length by commensuratelyincreasing the path within the reference arm 106 of OCT system 100.

Because of the fundamental differences in the OCT measurement withrespect to the UF focus device due to influences such as immersionindex, refraction, and aberration, both chromatic and monochromatic,care must be taken in analyzing the OCT signal with respect to the UFbeam focal location. A calibration or registration procedure as afunction of X, Y, and Z should be conducted in order to match the OCTsignal information to the UF focus location and also to the relative toabsolute dimensional quantities.

Observation of an aim beam may also be used to assist the user todirecting the UF laser focus. Additionally, an aim beam visible to theunaided eye in lieu of the infrared OCT beam and the UF light beam canbe helpful with alignment provided the aim beam accurately representsthe infrared beam parameters. An aim subsystem 200 is employed in theconfiguration shown in FIG. 1. The aim beam 202 is generated by an aimbeam light source 201, such as a helium-neon laser operating at awavelength of 633 nm. Alternatively a laser diode in the 630-650 nmrange can be used. An advantage of using the helium neon 633 nm beam isits long coherence length, which would enable the use of the aim path asa laser unequal path-length interferometer (LUPI) to measure the opticalquality of the beam train, for example.

Once the aim beam light source 201 generates the aim beam 202, the aimbeam 202 is collimated using a lens 204. The size of the collimated beamis determined by the focal length of the lens 204. The size of the aimbeam 202 is dictated by the desired NA at the focus in the eye and themagnification of the beam train leading to the eye 68. Generally, theaim beam 202 should have close to the same NA as the UF light beam 6 inthe focal plane and therefore the aim beam 202 is of similar diameter tothe UF light beam 6 at the beam combiner 34. Because the aim beam 202 ismeant to stand-in for the UF light beam 6 during system alignment to thetarget tissue of the eye, much of the aim path mimics the UF path asdescribed previously. The aim beam 202 proceeds through a half-waveplate 206 and a linear polarizer 208. The polarization state of the aimbeam 202 can be adjusted so that the desired amount of light passesthrough the polarizer 208. The half-wave plate 206 and the linearpolarizer 208 therefore act as a variable attenuator for the aim beam202. Additionally, the orientation of polarizer 208 determines theincident polarization state incident upon the beam combiners 126, 34,thereby fixing the polarization state and allowing for optimization ofthe throughput of the beam combiners 126, 34. Of course, if asemiconductor laser is used as the aim beam light source 200, the drivecurrent can be varied to adjust the optical power.

The aim beam 202 proceeds through a system-controlled shutter 210 and anaperture 212. The system-controlled shutter 210 provides on/off controlof the aim beam 202. The aperture 212 sets an outer useful diameter forthe aim beam 202 and can be adjusted appropriately. A calibrationprocedure measuring the output of the aim beam 202 at the eye can beused to set the attenuation of aim beam 202 via control of the polarizer206.

The aim beam 202 next passes through a beam-conditioning device 214.Beam parameters such as beam diameter, divergence, circularity, andastigmatism can be modified using one or more well known beamingconditioning optical elements. In the case of the aim beam 202 emergingfrom an optical fiber, the beam-conditioning device 214 can simplyinclude a beam-expanding telescope with two optical elements 216, 218 inorder to achieve the intended beam size and collimation. The finalfactors used to determine the aim beam parameters such as degree ofcollimation are dictated by matching the UF light beam 6 and the aimbeam 202 at the location of the eye 68. Chromatic differences can betaken into account by appropriate adjustments of the beam conditioningdevice 214. In addition, the optical system 214 is used to imageaperture 212 to a desired location such as a conjugate location of theaperture 14.

The aim beam 202 next reflects off of fold mirrors 220, 222, which arepreferably adjustable for alignment registration to the UF light beam 6subsequent to the beam combiner 34. The aim beam 202 is then incidentupon the beam combiner 126 where the aim beam 202 is combined with theOCT beam 114. The beam combiner 126 reflects the aim beam 202 andtransmits the OCT beam 114, which allows for efficient operation of thebeam combining functions at both wavelength ranges. Alternatively, thetransmit function and the reflect function of the beam combiner 126 canbe reversed and the configuration inverted. Subsequent to the beamcombiner 126, the aim beam 202 along with the OCT beam 114 is combinedwith the UF light beam 6 by the beam combiner 34.

A device for imaging the target tissue on or within the eye 68 is shownschematically in FIG. 1 as an imaging system 71. The imaging system 71includes a camera 74 and an illumination light source 86 for creating animage of the target tissue. The imaging system 71 gathers images thatmay be used by the control electronics 300 for providing patterncentering about or within a predefined structure. The illumination lightsource 86 is generally broadband and incoherent. For example, the lightsource 86 can include multiple LEDs as shown. The wavelength of theillumination light source 86 is preferably in the range of 700 nm to 750nm, but can be anything that is accommodated by a beam combiner 56,which combines the viewing light with the beam path for the UF lightbeam 6 and the aim beam 202 (beam combiner 56 reflects the viewingwavelengths while transmitting the OCT and UF wavelengths). The beamcombiner 56 may partially transmit the aim wavelength so that the aimbeam 202 can be visible to the viewing camera 74. An optionalpolarization element 84 in front of the light source 86 can be a linearpolarizer, a quarter wave plate, a half-wave plate or any combination,and is used to optimize signal. A false color image as generated by thenear infrared wavelength is acceptable.

The illumination light from the light source 86 is directed down towardsthe eye using the same objective lens 58 and the contact lens 66 as theUF light beam 6 and the aim beam 202. The light reflected and scatteredoff of various structures in the eye 68 are collected by the same lenses58, 66 and directed back towards the beam combiner 56. At the beamcombiner 56, the return light is directed back into the viewing path viabeam combiner 56 and a mirror 82, and on to the viewing camera 74. Theviewing camera 74 can be, for example but not limited to, any siliconbased detector array of the appropriately sized format. A video lens 76forms an image onto the camera's detector array while optical elements80, 78 provide polarization control and wavelength filteringrespectively. An aperture or iris 81 provides control of imaging NA andtherefore depth of focus and depth of field. A small aperture providesthe advantage of large depth of field that aids in the patient dockingprocedure. Alternatively, the illumination and camera paths can beswitched. Furthermore, the aim light source 200 can be made to emitinfrared light that would not be directly visible, but could be capturedand displayed using the imaging system 71.

Coarse adjust registration is usually needed so that when the contactlens 66 comes into contact with the cornea of the eye 68, the targetedstructures are in the capture range of the X, Y scan of the system.Therefore a docking procedure is preferred, which preferably takes inaccount patient motion as the system approaches the contact condition(i.e. contact between the patient's eye 68 and the contact lens 66). Theviewing system 71 is configured so that the depth of focus is largeenough such that the patient's eye 68 and other salient features may beseen before the contact lens 66 makes contact with the eye 68.

Preferably, a motion control system 70 is integrated into the overallsystem 2, and may move the patient, the system 2 or elements thereof, orboth, to achieve accurate and reliable contact between the contact lens66 and the eye 68. Furthermore, a vacuum suction subsystem and flangemay be incorporated into the system 2, and used to stabilize the eye 68.Alignment of the eye 68 to the system 2 via the contact lens 66 can beaccomplished while monitoring the output of the imaging system 71, andperformed manually or automatically by analyzing the images produced bythe imaging system 71 electronically by means of the control electronics300 via the IO 302. Force and/or pressure sensor feedback can also beused to discern contact, as well as to initiate the vacuum subsystem. Analternate patient interface can also be used, such as that described inU.S. patent application Ser. No. 13/225,373, which is incorporatedherein by reference.

An alternative beam combining configuration is shown in the alternateembodiment of FIG. 2. For example, the passive beam combiner 34 in FIG.1 can be replaced with an active combiner 140 as shown in FIG. 2. Theactive beam combiner 140 can be a moving or dynamically controlledelement such as a galvanometric scanning mirror, as shown. The activecombiner 140 changes its angular orientation in order to direct eitherthe UF light beam 6 or the combined aim and OCT beams 202,114 towardsthe scanner 50 and eventually towards the eye 68 one at a time. Theadvantage of the active combining technique is that it avoids thedifficulty of combining beams with similar wavelength ranges orpolarization states using a passive beam combiner. This ability istraded off against the ability to have simultaneous beams in time andpotentially less accuracy and precision due to positional tolerances ofactive beam combiner 140.

Another alternate embodiment is shown in FIG. 3 and is similar to thatof FIG. 1 but utilizes an alternate approach to the OCT 100. In FIG. 3,an OCT 101 is the same as the OCT 100 in FIG. 1, except that thereference arm 106 has been replaced by a reference arm 132. Thisfree-space OCT reference arm 132 is realized by including a beamsplitter 130 after the lens 116. The reference beam 132 then proceedsthrough a polarization controlling element 134 and then onto a referencereturn module 136. The reference return module 136 contains theappropriate dispersion and path length adjusting and compensatingelements and generates an appropriate reference signal for interferencewith the sample signal. The sample arm of OCT 101 now originatessubsequent to the beam splitter 130. Potential advantages of this freespace configuration include separate polarization control andmaintenance of the reference and sample arms. The fiber based beamsplitter 104 of the OCT 101 can also be replaced by a fiber basedcirculator. Alternately, both the OCT detector 128 and the beam splitter130 might be moved together as opposed to the reference return module136.

FIG. 4 shows another alternative embodiment for combining the OCT beam114 and the UF light beam 6. In FIG. 4, an OCT 156 (which can includeeither of the configurations of OCT 100 or 101) is configured such thatan OCT beam 154 output by the OCT 156 is coupled to the UF light beam 6after the z-scan device 40 using a beam combiner 152. In this way, theOCT beam 154 avoids using the z-scan device 40. This allows the OCT 156to possibly be folded into the beam more easily and shortening the pathlength for more stable operation. This OCT configuration is at theexpense of an optimized signal return strength as discussed with respectto FIG. 1. There are many possibilities for the configuration of the OCTinterferometer, including time and frequency domain approaches, singleand dual beam methods, swept source, etc, as described in U.S. Pat. Nos.5,748,898; 5,748,352; 5,459,570; 6,111,645; and 6,053,613, for example.

The system 2 can be set to locate the surface of the capsule and ensurethat the light beam 6 will be focused on the lens capsule at all pointsof the desired opening. Imaging modalities and techniques describedherein, such as for example, Optical Coherence Tomography (OCT), such asPurkinje imaging, Scheimpflug imaging, confocal or nonlinear opticalmicroscopy, fluorescence imaging, ultrasound, structured light, stereoimaging, or other known ophthalmic or medical imaging modalities and/orcombinations thereof may be used to determine the shape, geometry,perimeter, boundaries, and/or 3-dimensional location of the lens andlens capsule to provide greater precision to the laser focusing methods,including 2D and 3D patterning. Laser focusing may also be accomplishedusing one or more methods including direct observation of an aimingbeam, or other known ophthalmic or medical imaging modalities andcombinations thereof, such as but not limited to those defined above.

Optical imaging of the anterior chamber and lens can be performed on thelens using the same laser and/or the same scanner used to produce thepatterns for cutting. This scan will provide information about the axiallocation and shape (and even thickness) of the anterior and posteriorlens capsule, the boundaries of the cataract nucleus, as well as thedepth of the anterior chamber. This information may then be loaded intothe laser 3-D scanning system or used to generate a three dimensionalmodel/representation/image of the anterior chamber and lens of the eye,and used to define the patterns used in the surgical procedure.

The above-described systems can be used to create bubbles within theanterior hyaloid vitreous of Berger's space. By creating a layer ofbubbles, Berger's space can be expanded, thereby separating theposterior capsule from the anterior hyaloid surface so that a posteriorcapsulotomy can be performed on the posterior portion of the lenscapsule with reduced risk of compromising the anterior hyaloid surface.

FIG. 5 shows a schematic representation of the anterior chamber, lens,and anterior vitreous of the eye. The eye includes a lens 412, a lenscapsule 402, an anterior cornea surface 418, stroma 416, a posteriorcorneal surface 420, an optical axis 422, an iris 414, and a hyaloidmembrane 425. The space between the posterior lens capsular surface andthe hyaloid membrane is the capsulo-hyaloidal interspace, also known asBerger's space. This region is filled with an aqueous liquid that isless viscous than the denser, more gelatinous vitreous humor. Inaccordance with many embodiments, bubbles can be produced within theanterior hyaloid vitreous of Berger's space using, as non-limitingexamples, the pulsed laser systems described above.

FIG. 6 is a schematic representation of using a laser to form a bubblewithin the anterior hyaloid vitreous of Berger's space. In this example,the laser beam 6 is focused to a point to cause dielectric breakdown andform plasma 432. The plasma 432 results in a cavitation bubble 434,which can persist for as long as hours, especially if unperturbed. Thecavitation bubble 434 causes the hyaloid membrane 425 to be displaced toform the shape as illustrated by a displaced hyaloid membrane 425′. Ascan be seen in this example, the formation of a bubble in a singlelocation can displace the hyaloid membrane such that it is further awayfrom the posterior portion of the lens capsule 402 in the vicinity ofthe solitary bubble location, but actually closer to the posteriorcapsule outside of that vicinity. Once established, a bubble will notprovide for efficient further expansion via cavitation due to the lackof available mass within the gas of the bubble as opposed to that of theliquid used to create it. The beam 6, however, can be relocated usingscanning systems 40 & 50 to produce bubbles elsewhere and create abroader and/or deeper bubble layer to further increase the volume ofBerger's space.

FIG. 7 shows an example of the results of such a scanning operation.Here, the beam 6 (not longer shown) has been translated using scanners40 & 50 (also not shown in this rendering) to generate a layer ofbubbles 434 that further expand Berger's space.

In many embodiments, the patient can be treated in a supine position sothat the gas generated subsequent to the laser creation of plasma andresultant cavitation rises to the posterior capsule. The rising bubblesserve to further separate the posterior capsule from the anteriorhyaloid surface.

FIG. 8 illustrates a method 500 for performing laser-assisted surgery onan eye, in accordance with many embodiments. Any suitable system can beused to practice the method 500, including any suitable system describedherein and known to a person of ordinary skill in the art.

In act 502, a laser is used to form a plurality of bubbles within theBerger's space of an eye to increase separation between the posteriorportion of the lens capsule and the anterior hyaloid surface. In act504, after forming the plurality of bubbles, the posterior portion ofthe lens capsule is incised. In many embodiments, the laser is used toperform the incising of the posterior portion of the lens capsule. Andin many embodiments, the laser is used to perform a capsulotomy on theposterior portion of the lens capsule.

Any suitable laser can be used to form the bubbles within the Berger'sspace and/or to incise the posterior portion of the lens capsule. Anexample of such a suitable system is described U.S. patent applicationSer. No. 11/328,970, in the name of Blumenkranz et al., entitled “METHODAND APPARATUS FOR PATTERNED PLASMA-MEDIATED LASER TREPHENATION OF THELENS AND CAPSULE IN THREE DIMENSIONAL PHACO-SEGMENTATION”, Pub. No.2006/0195076, the entire disclosure of which is incorporated herein byreference. In many embodiments, the laser is configured to emit a pulsedlaser beam into a focal point substantially aligned with the Berger'sspace. For example, the pulses of the pulsed laser beam can each have apulse duration between about 10 femtoseconds and about 30 nanoseconds.The pulsed laser beam can have a pulse repetition rate between about 10Hz and about 1 MHz. The energy of each laser pulse of the pulsed laserbeam can be between about 1 micro joule and about 20 micro joules. Thepulsed laser beam can have a wavelength between about 500 nanometers andabout 1,100 nanometers. When using the laser to form the bubbles, thelaser can be irradiated into a focal point substantially aligned withthe Berger's space by using an operating numerical aperture of betweenabout 0.005 and about 0.5, a focal spot size diameter between about 1micron and about 20 microns, and/or with a fluence between about 2joules per square centimeter and about 200 joules per square centimeter.

Although the above steps show method 500 of treating a patient inaccordance with embodiments, a person of ordinary skill in the art willrecognize many variations based on the teaching described herein. Thesteps may be completed in a different order. Steps may be added ordeleted. Some of the steps may comprise sub-steps. Many of the steps maybe repeated as often as if beneficial to the treatment.

One or more of the steps of the method 500 may be performed with thecircuitry as described herein, for example one or more of the processoror logic circuitry such as the programmable array logic for fieldprogrammable gate array. The circuitry may be programmed to provide oneor more of the steps of method 500, and the program may comprise programinstructions stored on a computer readable memory or programmed steps ofthe logic circuitry such as the programmable array logic or the fieldprogrammable gate array, for example.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated herein by reference intheir entirety to the same extent as if each reference were individuallyand specifically indicated to be incorporated by reference and were setforth in its entirety herein.

While preferred embodiments of the present disclosure have been shownand described herein, it will be obvious to those skilled in the artthat such embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will be apparent to those skilledin the art without departing from the scope of the present disclosure.It should be understood that various alternatives to the embodiments ofthe present disclosure described herein may be employed withoutdeparting from the scope of the present invention. Therefore, the scopeof the present invention shall be defined solely by the scope of theappended claims and the equivalents thereof.

What is claimed is:
 1. A method for performing laser-assisted surgery onan eye having a lens capsule, an anterior hyaloid surface, and aBerger's space between a posterior portion of the lens capsule and theanterior hyaloid surface, the method comprising: forming, by a laser, aplurality of bubbles in a layer pattern which is located within theBerger's space, the layer pattern occupying a central area of theBerger's space including an optical axis of the eye and extendinglaterally in directions transverse to the optical axis without extendingacross the anterior hyaloid surface, to increase separation between theposterior portion of the lens capsule and the anterior hyaloid surface;and after forming the plurality of bubbles, incising the posteriorportion of the lens capsule.
 2. The method of claim 1, wherein the stepof incising the posterior portion of the lens capsule is performed bythe laser.
 3. The method of claim 2, wherein the step of incising theposterior portion of the lens capsule includes incising a capsulotomy onthe posterior portion of the lens capsule.
 4. The method of claim 1,wherein the laser is configured to emit a pulsed laser beam into a focalpoint aligned with the Berger's space.
 5. The method of claim 4, whereinthe pulses of the pulsed laser beam each have a pulse duration between10 femtoseconds and 30 nanoseconds.
 6. The method of claim 4, whereinthe pulsed laser beam has a pulse repetition rate between 10 Hz and 1MHz.
 7. The method of claim 4, wherein the energy of each laser pulse ofthe pulsed laser beam is between 1 micro joule and 20 micro joules. 8.The method of claim 4, wherein the pulsed laser beam has a wavelengthbetween 500 nanometers and 1,100 nanometers.
 9. The method of claim 1,wherein the step of forming a plurality of bubbles comprises irradiatingthe laser into a focal point aligned with the Berger's space by anoperating numerical aperture of between 0.005 and 0.5.
 10. The method ofclaim 1, wherein the step of forming a plurality of bubbles comprisesirradiating the laser into a focal point which is aligned with theBerger's space and has a focal spot size diameter between 1 micron and20 microns.
 11. The method of claim 1, wherein the step of forming aplurality of bubbles comprises irradiating the laser into a focal pointwhich is aligned with the Berger's space and has a fluence between 2joules per square centimeter and 200 joules per square centimeter.
 12. Amethod for performing laser-assisted surgery on an eye having a lenscapsule, an anterior hyaloid surface, and a Berger's space between aposterior portion of the lens capsule and the anterior hyaloid surface,the method comprising: delivering, by a laser system, a focal spot of apulsed laser beam to the eye to form a plurality of bubbles in a layerpattern which is located within the Berger's space, the layer patternoccupying a central area of the Berger's space including an optical axisof the eye and extending laterally in directions transverse to theoptical axis without extending across the anterior hyaloid surface, toincrease separation between the posterior portion of the lens capsuleand the anterior hyaloid surface, wherein the pulsed beam had aplurality of laser pulses having a wavelength of 500 to 1100 nm, a pulseduration of 10 fs to 30 ns, a repetition rate of 10 Hz to 1 MHz, and anenergy of 1 to 20 μJ, and wherein the focal spot has a diameter of 1 to20 microns; and after forming the plurality of bubbles, incising theposterior portion of the lens capsule.
 13. The method of claim 12,wherein the step of incising the posterior portion of the lens capsuleis performed by the laser.
 14. The method of claim 12, wherein the stepof incising the posterior portion of the lens capsule includes incisinga capsulotomy on the posterior portion of the lens capsule.
 15. Themethod of claim 12, wherein the step of forming a plurality of bubblescomprises irradiating the laser into a focal point aligned with theBerger's space by an operating numerical aperture of between 0.005 and0.5.
 16. The method of claim 12, wherein the step of forming a pluralityof bubbles comprises irradiating the laser into a focal point which isaligned with the Berger's space and has a fluence between 2 joules persquare centimeter and 200 joules per square centimeter.